Allowed to build-depend a pkg in main on a pkg in non-free?

[Roland Fehrenbacher <rfehren@debian.org>]

Hi,

a quick question to the list, since I didn't find an answer after a
significant time of searching:

Is it allowed to have a source package with a build dependency on a pkg in
non-free (in this particular case nvidia-cuda-toolkit) and resulting
binary packages to go partly to main and others to contrib? Current case
of doubt is the relion source package for which I would like to build
non-cuda (should go to main, no dependencies out of main) and
cuda-enabled (would go to contrib) binary package versions.

See https://salsa.debian.org/med-team/relion

Thanks,

Roland